Known mechanisms for supplying lubricant to bearings of camshaft journals have been provided for an engine including a camshaft and the bearings. The camshaft is provided in a cylinder head and includes camshaft journals. Each of the bearings rotatably supports one of the camshaft journals of the camshaft.
Patent Document 1 discloses a lubricant supply mechanism for camshaft journals. The mechanism includes oil passages for the camshaft journals, which extend upward from an oil gallery in a cylinder head, and are connected to lower portions of bearings of the camshaft journals. The mechanism supplies the lubricant through the oil passages for the camshaft journals to the bearings from below.
Patent Document 2 discloses a lubricant supply mechanism for camshaft journals, which includes first to third oil passages. The first oil passage guides the lubricant from a hydraulic power source to one of bearings of the camshaft journals. The second oil passage penetrates one of the camshaft journals of a camshaft, which rotates and slides with respect to the bearing connected to the first oil passage, and receives the lubricant intermittently in accordance with the rotation of the camshaft. The third oil passage is located above the camshaft journals, and supplies the lubricant, which has been supplied from the second oil passage, from a position above the camshaft to a bearing of another camshaft journal.